The traditional method for the collection of small quantities of blood from a patient utilizes mechanical perforation of the skin with a sharp device such as a metal lancet or needle. This procedure has many drawbacks, two of which are the possible infection of health-care workers or the public at large with the device used to perforate the skin, and the costly handling and disposal of biologically hazardous waste.
When skin is perforated with a sharp device such as a metal lancet or needle, biological waste is created in the form of the "sharp" which is contaminated by the patient's blood and/or tissue. If the patient is infected with any number of blood-born agents, such as human immunodeficiency virus (HIV) which causes autoimmune deficiency syndrome (AIDS), hepatitis virus, or the etiological agent of other diseases, the contaminated sharp can pose a serious threat to others who might come in contact with it. There are many documented instances of HIV infection of medical workers who were accidentally stabbed by a contaminated sharp.
Disposal of sharps is also a major problem. Disposal of contaminated materials poses both a logistics and a financial burden on the end user such as the medical institution. In the 1980s, numerous instances of improperly disposed biological wastes being washed up on public beaches have occurred. The potential for others, such as intravenous drug users, to obtain improperly disposed needles is also problematic.
There exists an additional drawback of the traditional method of being stabbed by a sharp instrument for the purpose of drawing blood. Often, the stabbing procedure must be repeated before sufficient blood is obtained. This can cause significant stress and anxiety in the patient.
Clearly the current procedure for puncturing skin for the purpose of drawing blood has significant inherent problems. These problems arise because a sharp instrument is used in the procedure. Thus, a need exists for a technique to puncture skin which does not use a sharp instrument. This method would obviate the need for disposal of contaminated instruments, and reduce the risk of cross infection.
Lasers have been used in recent years as a very efficient precise tool in a variety of surgical procedures. Among potentially new sources of laser radiation, the rare-earth elements are of major interest for medicine. The most promising of these is a YAG (yttrium, aluminum, garnet) crystal doped with erbium (Er) ions. With the use of this crystal, it is possible to build an erbium-YAG (Er:YAG) laser which can be configured to emit electromagnetic energy at a wavelength (2.94 microns) which is strongly absorbed by water. When tissue, which consists mostly of water, is irradiated with radiation at or near this wavelength, it is rapidly heated. If the intensity of the radiation is sufficient, the heating is rapid enough to cause the vaporization of tissue. Some medical uses of Er:YAG lasers have been described in the health-care disciplines of dentistry, gynecology and ophthalmology. See, e.g., Bogdasarov, B. V., et al., "The Effect of YAG:Er Laser Radiation on Solid and Soft Tissues," Preprint 266, Institute of General Physics, Moscow, 1987; Bol'shakov, E. N. et al., "Experimental Grounds for YAG:Er Laser Application to Dentistry," SPIE 1353:160-169, Lasers and Medicine (1989).